1. Field of the Invention
The present invention relates to a method for recovering from a sun transit in a communication of a very small aperture terminal (VSAT), in which a sun transit outrage (STO) is prevented by using a sun transit recovering algorithm, thereby making it possible to apply the very small aperture terminal (VSAT) to the satellite communication.
2. Description of the Prior Art
Generally, the communication system of the very small aperture terminal (VSAT) in which a still track satellite is used includes a VSAT central station (VCS), a network management system (NMS), and a VSAT remote station (VRS). In this communication system constituted as above, when the sun reaches near the boresight axis of an antenna, an STO phenomenon occurs, with the result that the communication system is influenced by the additional noise power of the sun. Consequently, the reliability of the communication system drops to below an average quality which is tolerable in an antenna communication system. Particularly, in a communication system using a still track satellite, the STO phenomenon occurs once every day near the spring equinox and the autumnal equinox, and therefore, problems are encountered in carrying out the communications.
Meanwhile, U.S. Pat. No. 5,271,039 discloses a local oscillating device for controlling the frequency in a communication system. This device includes: a satellite-modulated signal generating means; a local oscillating means provided with an oscillator for generating an oscillating frequency to furnish a sampling frequency to be controlled; an A/D converter for receiving the satellite-modulated signals to convert them into digital signals by using sampling clocks at the local oscillating means; a demodulating means for demodulating the received digital signals by using symbol clocks, for reproducing the symbol clocks to demodulate so as to detect the phase difference information between the symbol clocks and sampling clocks, and for receiving the digital signals from the A/D converter; and a control means for controlling the oscillating frequency of the local oscillating means based on the phase difference information between the symbol clocks and the sampling clocks, and for coupling with the demodulating means to output an oscillating frequency pre-set by the local oscillating means.
However, this apparatus could not solve the above described problem.